Although no-one ever asked Pachacuti why he put his residential palace up so far into the Andes, we can guess that it was only partly for the beauty of his surroundings. Pachacuti came to power in the traditional Incan way: by warfare. The Inca empire had its foundations around 1200 AD. It remained small, one of several competing regional polities, until late in the reign of the eighth Inca king, Viracocha, about 1438 AD. At that time, the Inca capital at Cuzco was attacked by the Chancas, a powerful group who lived to the north. Viracocha fled, but his son, Inca Yupanqui, refused to cede and fought his way to victory.
After his victory, Inca Yupanqui took the name Pachacuti (which means "cataclysm"), and began the empire building for which the Inca are renowned.